Lanthanum phosphide is an

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

lanthanum Lanthanum is a chemical element with the symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lantha ...

and

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

with the chemical formula LaP.

Synthesis

Lanthanum phosphide can be made by heating lanthanum metal with excess phosphorus in a vacuum: :: 4 La + P₄ → 4 LaP

Physical properties

Lanthanum phosphide forms black crystals of a

cubic system In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals. There are three main varieties of ...

, space group Fmm, cell parameters a = 0.6025 nm, with number of formulas per unit cell Z = 4. The crystals are very unstable and decompose in the open air.

Electronic properties

Lanthanum phosphide is an example of a

strongly correlated material Strongly correlated materials are a wide class of compounds that include insulators and electronic materials, and show unusual (often technologically useful) electronic and magnetic properties, such as metal-insulator transitions, heavy fermion ...

, complicating theoretical prediction of its properties. According to HSE06 calculations, lanthanum phosphide has been theoretically predicted to have an indirect band gap of 0.25 eV along the Γ-X direction. According to HSE06 calculations with spin-orbit coupling, the band gap is predicted to be a direct gap of 0.72 eV at the X point. Using EVGGA, the compound is predicted to have a band gap of 0.56 eV along the Γ-X direction. FP-LAPW has predicted an indirect gap of 0.33 eV along the Γ-X direction.

Chemical properties

Lanthanum phosphide reacts with water, releasing highly toxic

phosphine Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting ...

gas: :: LaP + 3H₂O → La(OH)₃ + PH₃

Uses

Lanthanum phosphide compound is a

semiconductor A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glas ...

used in high power, high frequency applications, and in

laser diode file:Laser diode chip.jpg, The laser diode chip removed and placed on the eye of a needle for scale A laser diode (LD, also injection laser diode or ILD, or diode laser) is a semiconductor device similar to a light-emitting diode in which a di ...

Lanthanum polyphosphide

In addition to the simple phosphide, LaP, lanthanum and phosphorus can also form phosphorus-rich compounds such as LaP₂ LaP₅ and LaP₇.